Vinyl esters are a well known class of curable materials prepared by reaction of monounsaturated monocarboxylic acids and polyepoxides. Typically said vinyl esters are diluted with one or more copolymerizable ethylenically unsaturated monomers to provide the more easily processed vinyl ester resins.
Norbornyl terminated unsaturated polyesters and polyesteramides are also well known as curable materials. Typically said norbornyl terminated unsaturated polyesters and polyesteramides are prepared by reaction of dicyclopentadiene, maleic anhydride, water, one or more polyols and, in the case of the polyesteramide, one or more polyamines. One or more copolymerizable ethylenically unsaturated monomers are typically blended with the aforesaid polyesters and polyesteramides.
Although both vinyl esters and norbornyl terminated unsaturated polyesters and polyesteramides provide many useful properties when used to prepare a variety of cured articles, there is substantial room for improvement in many of the properties provided by said resins. Notably, the mechanical properties, corrosion resistance, heat resistance, steam resistance and the like of one or both of the aforesaid resins are frequently deficient and would benefit from improvement. To this end, the present invention provides mixtures of vinyl esters and norbornyl terminated unsaturated polyesters or polyesteramides which provide improvements in one or more of the aforesaid properties.
It is recognized that U.S. Pat. No. 4,310,647 teaches preparation of curable mixtures of halogenated bis(dicyclopentadienyl)fumarate with vinyl esters, however, said bis(dicyclopentadienyl)ester is monomeric and thus does not contain the ester or esteramide chain required by the present invention (i.e., no polyols or polyamines are used to prepare these compositions). More importantly, halogenation of the bis(dicyclopentadienyl)esters removes the cyclopentenyl unsaturation inherent to the norbornyl terminated unsaturated polyester or polyesteramide component used in the present invention. This unsaturation is critical to provide the benefits of the present invention, especially increased heat resistance.